1. Field of the Invention
The invention relates to a device for utilizing combustion and waste materials containing carbon and ash by means of gasification.
The device can be used wherever waste materials containing carbon and ash are gasified with oxygen or an oxidizing agent containing oxygen at increased or atmospheric pressure in a flame reaction at temperatures of at least 1100.degree. C.
2. Description of the Related Art
Combustion materials containing ash include solid fuels with greater or lesser ash content, such as brown coal and hard coal and their cokes, as well as oil and tars slightly loaded with inorganic components and mixtures thereof with solids. Waste materials containing ash include solids and liquids found in the waste and recycling industry, in particular, such as communal and industrial sludges, used oils, oils containing PCBs, plastic and household waste fractions and their processing products, light shredder from the processing of auto, cable and electronic scrap, and contaminated aqueous solutions.
In gas production technology, the autothermal fluidized gasification of solid, liquid and gaseous combustion materials has been known for years. The ratio of combustion material to gasification agents containing oxygen is selected in such a way that, for reasons of synthesis gas quality, the higher carbon compounds are completely cracked into synthesis gas components such as CO and H.sub.2, while the inorganic components are extracted as molten slag (see, i.e., J. Carl, P. Fritz, Noell-Konversion-Verfahren, EF Verlag fuer Energie- und Umwelttechnik GmbH, 1996, p. 39).
In various known systems the gasification gas and the molten slag can be extracted separately or jointly from the reaction chamber of the gasification device (see, i.e., F. J. Schweitzer, Thermoselect-Verfahren, EF Verlag fuer Energie- und Umwelttechnik GmbH 1994, p. 156).
German reference 4446803 A1 discloses that refractory-grade lined systems or cooled systems can be provided as the interior border for the reaction chambers of gasification systems.
Gasification systems equipped with refractory-grade linings have the advantage of lower heat losses, and thus provide energy-efficient conversion of the supplied combustion materials. However, such systems can be used only for ash-free combustion materials, because the molten slag that flows down the interior surface of the reaction chamber during the fluidized gasification process dissolves the refractory-grade lining. This means that only limited reactor runs are possible before costly relining becomes necessary.
To overcome this disadvantage, cooled systems based on the principle of a membrane wall have been created for combustion materials containing ash. The cooling initially causes a solid slag layer to form on the surface associated with the reaction chamber. The thickness of the solid slag layer increases until further slag ejected from the gasification area runs down this wall as a liquid and flows out of the reaction chamber, e.g., together with the gasification gas. Such systems are highly resistant and ensure long reactor runs. A substantial disadvantage of these systems, however, is that up to roughly 5% of the furnished energy is transferred to the cooled screen and is available only in the form of hot water or low-pressure steam. This can be a considerable disadvantage, especially in the case of low-caloric combustion materials and waste materials.
Various combustion and waste materials (e.g., oils containing heavy metals or light ash, tars and tar-oil-solid sludges) contain too little ash to form an adequate protective slag layer on the cooled reactor walls. This, too, leads to energy losses. On the other hand, in reactors with refractory-grade linings, the ash content of such materials is too high to avoid the melting or dissolution of the refractory-grade layer or to achieve sufficiently long reactor runs before re-lining is necessary.